Re: Weather station and lightning

From: w_tom (w_tom1_at_hotmail.com)
Date: 12/13/04 

Date: Mon, 13 Dec 2004 00:31:28 -0500

  Lets see. The telco installs wires overhead everywhere in
town and connected to their $multimillion computer. Since
they don't use opto-isolation, then clearly telephone service
must be shutdown during every thunderstorm.

  So that operators don't get shocked, 911 emergency operators
remove their headsets and leave the room during every
thunderstorm.

  So that expensive transmitter equipment is not destroyed, TV
and FM radio stations atop the Empire State Building (that is
struck 25 times annually) shut down commercial broadcasting
during thunderstorms.

  No. They all maintain service, do not use opto-isolation or
fiber optics, and must never suffer damage or service
interruption during a direct strike. The principles are quite
sound, well proven since before WWII, and use the one
protection component that all protection systems require - a
single point earth ground. Others such as John Popelish and
Watson A.Name are saying same. Opto isolators can only
enhance existing protection. But without that essential earth
ground, then opto isolators are quickly overwhelmed - made
ineffective.

  Other sources also demonstrate the principles:
  
http://www.erico.com/public/library/fep/technotes/tncr002.pdf
   http://www.harvardrepeater.org/news/lightning.html
   http://www.telematic.com/index.htm
   http://scott-inc.com/html/ufer.htm
Then the benchmark in surge protection:
   http://www.polyphaser.com/ppc_technical.asp .

  There is one an only one component that every lightning
protection system must have - single point earth ground.
Those other devices (protector diodes, opto-isolators,
lightning rods) and peripheral devices to the main protection
device - earth ground. Notice professionals cited above all
discuss the most important protection component - earth
ground. And only a few of your responders here also posted
different protection devices always connected to the lighting
protection component - earth ground.

  Nothing will stop, block, or absorb what even 3 miles of sky
could not stop. As Ben Franklin demonstrated and as John
Popelish demonstrates in both newsgroups - divert lightning to
earth before it can get to that computer. That is what the
lightning rod or overhead catenary wire does. That is also
why the RS-232 wire must make a connection to single point
earth ground before rising back up to connect to computer.
That is even required of telephone, satellite dish, and TV
cable wire before it enters your building - for same lightning
protection reasons. There is no effective protector for
cabling to computer if it does not make a short (less than 10
foot) connection to earth ground.

Jim Thompson wrote:
> An ordinary opto-coupler WILL NOT BLOCK LIGHTNING! Most are
> perhaps good to 3000V.
>
> You need fiber in between to ensure enough isolation.

Relevant Pages

  • Re: Lightning and computer?
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  • Re: How to PostMortem?
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